A fixed colloidal crystal has been conventionally known, in which colloidal particles are regularly arranged without making adjacent colloidal particles substantially contact with one another by dispersing the colloidal particles in a solvent containing a polymerizable substance and polymerizing the polymerizable substance (refer to Patent Document 1, for example).
A fixed colloidal crystal is described in Patent Document 1, in which a polycrystal of colloidal particles of silicon oxide is fixed by repulsion of the polymer chain by mixing silicon oxide having a particle size of 136 nm into ethylene dimethacrylate and methyl methacrylate so that the content of silicon oxide becomes 31% by weight.
However, the peak wavelength in the reflection spectrum of the fixed colloidal crystal described in Patent Document 1 is about 530 nm, and arbitrary play of color could not be exhibited over a wide wavelength range (343 to 808 nm) from purple to red.
On the other hand, there is a method of packing with colloidal particles consisting of fine particles of silicon oxide, or the like in a liquid such as water by a closest packing method (refer to Patent Document 2, for example). It is described in Patent Document 2 that packing with colloidal particles can be performed in a short time by closest packing by irradiating the liquid containing the fine particles with an ultrasound wave.
However, in the method described in Patent Document 2, it is necessary to vaporize or volatilize the liquid with an ultrasound wave and colloidal particles cannot be always packed in a short time depending on the concentration and the composition of the liquid. Therefore, there are problems in terms of mass productivity and cost.
There is a method of manufacturing a colloidal crystal that is fixed with a polymer by polymerizing monomers in which colloidal particles are dispersed (refer to Patent Document 3, for example).
However, the colloidal crystal obtained in the method described in Patent Document 3 may possibly not exhibit sufficient play of color because the method does not intentionally control the size of the single crystal. That is, the fixed colloidal crystal is constituted of a polycrystal containing many single crystals. The play of color means a change in hue accompanied with change of viewing angle as seen in the jewel opal. One of the reasons why the play of color can be seen is considered that various crystal faces can be seen in the polycrystal due to the many single crystals described above. When the size of the single crystal is not intentionally controlled, the polycrystal may possibly be constituted of small single crystals. When the size of the single crystal is too small, visibility of the polycrystal deteriorates, and sufficient play of color cannot be exhibited. A colloidal crystal that does not exhibit sufficient play of color is not suitable for an architectural material, a fashion accessory, an optical material, and the like.